Previous studies at University of Illinois Temporomandibular Joint and Facial Pain Research Center have established a psychophysiologic basis for the myofascial pain-dysfunction (MPF) syndrome. The present research program will continue to focus on the physiologic aspects of the disorder with particular emphasis on the differences between pain of psychophysiologic origin (MPD) and that of organic etiology (TMJ). Among the methods to be used in studying the psychophysiologic parameters are signal detection theory and the measurement of evoked potentials. We also will explore in greater depth the psychosocial variables that may affect treatment response and how they may be modified. The pathological tissue changes in masticatory muscle, TMJs and related structures associated with the MPD and TMJ syndromes will be studied using histochemical, biochemical, immunochemical and microprobe x-ray analysis techniques. These findings will be correlated with improved radiographic (arthrography and tomography) examinations and clincial observations. Preliminary studies in normal animals and experimental models of pathological states will form the basis for the subsequent human investigation. The third major investigative area will concern itself with critical evaluation of treatment modalities for MPD and TMJ disorders and the accumulation of data on the occurrence, causes and progression of internal derangements of the TMJ. The proposed research should provide a better understanding of disorders of the TMJ and associated structures, lead to more effective preventive and therapeutic measures, and develop general information applicable to other somatic pain disorders of psychophysiologic origin.